Karyotypic differences between cells from placenta and other fetal tissues

Six cases are reported with discrepancies between the karyotypes of placental cells and cells from other fetal tissue. The respective findings were: 48, + 7, + 18 resp. 47, + 18. 46,i(18q) resp. 46,del18(p11). 46,XX resp. 46,XX/47,XXX. 46,X,Yq+ and 46,XY resp. 46,XY. 46/47, + 12 resp. 46. 46/47, + 5 resp. 46. These differences were found in both early and term pregnancies. Care should be taken in deducing the fetal karyotype from the chromosomal pattern of placental cells.